1. Field of the Invention
The present invention relates to a wiring circuit substrate used for mounting electronic devices, such as integrated circuits (ICs) and large scale integrated circuits (LSI circuits). Particularly, the invention relates to a wiring circuit substrate that allows high-density mounting to be implemented.
Furthermore, the present invention relates to a manufacturing method for the aforementioned wiring circuit substrate.
2. Description of the Related Art
FIGS. 54A to 54F and 55A to 55C are used to describe a conventional example of a high-density-mounting wiring circuit substrate. These figures are cross-sectional views illustrating a manufacturing method for the conventional wiring circuit substrate in the order of steps (A) to (I) described below.
Step (A)
First of all, as shown in FIG. 54A, a base 1 is prepared. The base 1 is made of an insulating sheet having a thickness of 25 to 100 xcexcm. In the base 1, interlayer-connecting openings 2 are formed by using a punching machine or a drill or by performing laser processing.
Step (B)
Subsequently, as shown in FIG. 54B, conductive paste 3 (made of a main material, for example, such as silver or copper) is filled into the openings 2 by using a printing method for example. Thereby, the insulating base 1 is arranged to be a semi-cured sheet A in which the conductive paste 3 is filled into the openings 2.
Step (C) and Step (D)
Subsequently, as shown in FIG. 54C, metal foils 4 made of, for example, copper, are individually arranged over two faces of the sheet A. Then, as shown in FIG. 54D, the metal foils 4 are overlaid by using a pressing/heating press. Thereby, a multilayer body is formed such that the metal foils 4 are formed on the two faces, an insulating sheet is provided therebetween, and the metal foils 4 on the two faces are electrically connected to each other via the conductive paste 3 in the openings 2.
Step (E)
Subsequently, resist films 5 are formed on the metal foils 4. The resist films 5 have the same pattern as that of conductor circuits that will be formed. FIG. 54E shows a state after the resist films 5 are formed.
Step (F)
Subsequently, using the aforementioned resist films 5 as masks, etching is performed for the aforementioned metal foils 4, thereby forming conductor circuits 6, as shown in FIG. 54F. According to the above, layers are separated and arranged on the two faces via the insulating sheet (base) 1, and a multilayer body B having the conductor circuits 6 interlayer-connected to each other via the conductive paste 3 in the opening 2 is formed.
Step (G)
Subsequently, as shown in FIG. 55A, on individual two faces of the aforementioned multilayer body B, insulating sheets la having openings 2 filled with conductive paste 3 and metal foils 4a are overlapped with each other. Thereafter, these component members are stacked with each other by using a press, and a multilayer body C is thereby formed.
Step (H)
Subsequently, as shown in FIG. 55B, resist films 5 are selectively formed on the metal foils 4a on two faces of the multilayer body C.
Step (I)
Subsequently using the resist films 5 as masks, etching is selectively performed for the metal foils 4a, thereby performing patterning therefor to form wiring films 6a, as shown in FIG. 55C. Thereby, a wiring circuit substrate 7 having four layers of the conductor circuits 6 and 6a are formed.
FIGS. 56A to 56G are used to explain another conventional example of a high-density-mounting wiring circuit substrate. These figures are cross-sectional views illustrating a manufacturing method for the conventional wiring circuit substrate in the order of steps (A) to (G) described below.
Step (A)
For example, as shown in FIG. 56A, a metal foil 10 (having a thickness of, for example, 18 xcexcm) made of a copper material is prepared. Then, on the metal foil 10, conductive protrusions 11 are formed by a printing method via conductive paste (made of a main material such as a silver or copper material) and a metal plate, and then, are heated and cured. The protrusions 11 are thus formed so as to have thicknesses, for example, ranging from 100 to 300 xcexcm.
Step (B)
Subsequently, as shown in FIG. 56B, an insulating adhesive sheet 12 is adhered onto the face on which the protrusions 11 of the aforementioned metal foil 10 are formed. For the adhesive sheet 12, an adhesive sheet having a thickness smaller than the thicknesses of the protrusions 11 is used. Thereby, the top of each of the protrusions 11 protrudes from the surface of the adhesive sheet 12. A multilayer body A is produced that has a configuration in which the protrusions 11 are formed on the metal foil 10 and the adhesive sheet 12 is adhered onto the surface of the metal foil 10 in a state of allowing the top of each the protrusions 11 to protrude therefrom.
Step (C) and Step (D)
Subsequently, as shown FIG. 56C, a metal foil 13 similar to the aforementioned metal foil 10 is arranged over the surface of the adhesive sheet 12, then, as shown in FIG. 56D, the metal foil 13 is overlaid on the adhesive sheet 12 and the protrusions 11 according to a heating-pressing method. Thereby, a multilayer body B is produced.
Step (E)
Subsequently, for example, resist films for which patterning is performed are formed on the metal foils 10 and 13 individually formed on two faces of the multilayer body B. Then, etching is performed for the metal foils 10 and 13 by using the resist films as masks, thereby forming conductor circuits 14 and 15. FIG. 56E shows a configuration where the resist films used as masks are removed after the conductor circuits 14 and 15 are formed.
Step (F)
Subsequently, two multilayer bodies a are prepared. Each of the multilayer body (a) is formed by the same method as that for the multilayer body (A) shown in FIG. 48B. As shown in FIG. 56F, the two multilayer bodies (a) are individually arranged over two faces of the aforementioned multilayer body (B).
Step (G)
The aforementioned multilayer body (B) is sandwiched by the multilayer bodies (a), and the integrated body is pressed from the sides of two faces thereof according to the aforementioned heating-pressing method. Thereby, a wiring circuit substrate 16 as shown in FIG. 56G is produced.
Subsequently, a still another conventional technique will be explained. FIGS. 57A to 57E and 58A to 58D show a production process of still another wiring circuit substrate.
Step (A)
As shown in FIG. 57A, a copper-plated laminated plate 400a is prepared for forming a hole 400b for connection therein by drilling or laser processing. The numeral 400c is an insulating sheet to serve as the base member for the laminated plate 400a, and 400d, 400d are copper foils formed on both sides of the insulating sheet 400c. 
Step (B)
Subsequently, as shown in FIG. 57B, a copper plating layer 400e is formed on the entire surface by an electroless plating process and a subsequent electrolytic plating process.
Step (C)
Subsequently, as shown in FIG. 57C, the hole 400b is filled with an insulating resin 400f, such as an epoxy.
Step (D)
Subsequently, as shown in FIG. 57D, both sides of the laminated plate 400a is smoothed by mechanical polishing. Thereafter, another copper plating layer 400g is formed by an electroless plating process and a subsequent electrolytic plating process. Accordingly, the insulating resin 400f filling up the hole 400b is covered by the copper plating layer 400g. 
Step (E)
Subsequently, as shown in FIG. 57E, a wiring film 400h is formed by patterning the copper plating layers 400g, 400d, 400e on both sides of the laminated plate 400a. The etching operation is executed by applying a resist film, exposing and developing the same so as to form a mask pattern, and selective etching with the mask pattern used as the mask. After the etching, the resist film is eliminated.
Step (F)
Subsequently, as shown in FIG. 58A, an insulating resin 400i, 400i is coated on both sides of the laminated plate 400a. Thereafter, a hole 400j to be a through hole is formed in the insulating resin 400i by a laser beam. At the time, the residual resin adhered on the surface of the copper foil 400d should be eliminated by using a washing liquid.
Step (G)
Subsequently, as shown in FIG. 58B, a copper plating layer 400k is formed on both sides of the laminated plate 400a by an electroless plating process and an electrolytic plating process.
Step (H)
Subsequently, as shown in FIG. 58C, a circuit 400l is formed by patterning the copper plating layers 400k on both sides of the laminated plate 400a. The etching operation is executed by selective etching with a mask formed by patterning a resist film by exposing and developing used as the mask. Thereafter, the resist film used as the mask is eliminated.
Step (I)
Subsequently, as shown in FIG. 58D, both sides of the laminated plate 400a are covered selectively by a solder resist 400m. Accordingly a wiring circuit substrate 400n is completed.
However, the conventional example shown in FIGS. 54 and 55 arises problems as described the followings. First, the openings 2 in the insulating sheet 1 are filled with the conductive paste 3 made of a main material such as expensive silver material and are used for interlayer connection. This arises a problem of increasing costs. Particularly, since arrangement density of the openings 2 is required to be increased according to an increasing demand for high-density mounting, the increase in costs becomes noticeable so as not to be ignored.
Second, when the conductive paste 3 is filled into the openings 2, the conductive material is adhered to portions other than the openings 2, although the amount thereof is very small. This arises a problem of reducing the insulation resistance, particularly in a high-humidity environment.
Third, when press-overlaying is performed after the openings 2 are formed in the insulating sheet 1, the insulating sheet 1 is forced to horizontally extend. Thereby, positional deviation of the openings 2 occurs. Even by performing correction thereof and making openings, the correction is not effective in the high-density pattern. The positional deviation of the openings 2 causes defective interlayer connection, thereby arising serious problems, which,cannot be ignored. Particularly, the problem is critical for the high-density-mounting wiring circuit substrate.
Fourth, the reliability of the connection between the metal foils 4 made of a copper material and the conductive paste 3 is insufficient. The conductive paste 3 filled into the openings 2 removes a solvent component so as to be a semi-cured state. The semi-cured conductive paste shrinks because of removal of the solvent component and the like, thereby reducing the volume of its own. In addition, in most cases, upper and lower faces of the conductive paste 3 become in a concave state. As a result, defective connection is apt to be caused between the metal foils 4, thereby arising a problem of reducing the reliability and the yield.
Subsequently, the conventional example shown in FIGS. 56A to 56G also arises problems as described the followings. First, using the protrusions 11 formed of the conductive paste also arises the problem of increasing costs.
Second, since a screen-printing method is used to form the protrusions 11 with the conductive paste, increase in the thickness thereof is restricted. Therefore, in most cases, screen-printing operations must be repeatedly performed to form the protrusions 11.
When the number of the printing operations is increased, the positional deviation of the protrusions 11 is apt to occur, and deformation of the protrusions 11 is thereby apt to occur. This develops a problem of reducing the reliability of the connections between the protrusions 11 and the metal foils 4. In addition, positioning operation for the screen-printing is very difficult and requires high-level skills, thereby causing a problem of requiring relatively long processing time.
These problems become increasingly apparent in proportion to reduction in the diameter of each of the protrusions 11. For example, for protrusions each having a diameter of 0.3 mm, two printing operations must be performed; and for protrusions each having a diameter of 0.2 mm, four printing operations must be performed. This is heavy work and disturbs improvement in the productivity, remaining problems to be solved for the provision of high-density wiring circuit substrates.
Third, still another problem arises in that heights of the protrusions 11 are likely varied. In specific, in the screen-printing method, since it is difficult to uniform thicknesses of films, heights of the protrusions 11 formed thereby are also likely to be variable. The variation in the thickness likely causes the connection between the metal foil 13 and the protrusions 11 to be defective. This results in arising a problem of reducing the yield and the reliability.
Fourth, in the manufacturing stage, the metal foil 10 basing the wiring circuit substrate is as thin as, for example, 18 xcexcm. Therefore, in the screen-printing sufficient care must be taken to prevent it from being wrinkled, deformed, and bent on the metal foil 13 side. Even a very minor operation problem could reduce the yield. This develops to the problem of increasing costs, which should not be neglected. Conversely, increasing the thickness of the metal foil 10 so as to obtain a strong base also causes a problem of disturbing the conductor circuits to be finely patterned.
One of problems common to the described conventional examples is that there are restrictions in making the high-density arrangement, that is, in the arrangement of fine interlayer connection. In the case of one example, the printing operation is difficult because of the reduction in the diameters of the openings and difficulty in filling the conductive paste into the openings. In the case of another conventional example, the difficulty in the printing operation increases in proportion to the reduction in the diameters in bump printing. Thus, according to the conventional technology, an opening having a diameter smaller than 200 xcexcm cannot be produced.
In addition, since the strength of the connection between the conductive paste and the copper foil is low, an excessively large area is required for the connection.
Next, the wiring circuit substrate shown in FIGS. 57A to 57E and 58A to 58D also involves problems.
A first problem is a poor adhesion property between the surface of the insulating resin 400f for filling the hole 400b and the copper plating layer 400g so as to easily generate adhesion failure.
Particularly at the time of mounting, in the case various members are connected with the area, there is a risk of generating fall-off.
Moreover, in order to solve the problem, the wiring circuit substrate needs to be designed so as not to superimpose the connecting points of the various members and the hole 400b formation area. Therefore, it gives the limitation in designing so as to be a cause for prohibiting a high density of the wiring circuit substrate.
A second problem is deflection of the surface of the copper plating layer 400k in the area with the hole 400j because the copper plating layer 400k is formed in the area with the hole 400j. 
Therefore, a wiring layer cannot be formed further on the copper plating layer 400k, and thus a multi-layer structure cannot be provided.
A third problem is the inability of ensuring a sufficient film thickness in the area with the hole 400j because the copper plating layer 400k is formed in the area.
That is, the copper plating layer 400k is formed by an electroless plating process and a subsequent electrolytic plating process. The film formation rate in the electroless plating process is low. Furthermore, the film thickness irregularity can easily be generated in the electrolytic plating process in relation to the electrolytic distribution. Therefore, even in a level difference part for forming the hole 400j, a film is formed with a thin film thickness so that a sufficient film thickness cannot be ensured. This point has prohibited realization of minuteness of the wiring circuit substrate.
The present invention is made to solve the above-described problems. An object of the invention is to provide a wiring circuit substrate that can be manufactured without problems such as bending, breaking, and deformation being caused and with dimensional stability being improved, thereby allowing improvement in the reliability of the connection between upper and lower conductor circuits, and in addition, allowing reduction in the cost for an upper-lower-conductor-circuit connecting device. Another object of the present invention is to provide a manufacturing method for the wiring circuit substrate.
Moreover, another object of the present invention is to provide a wiring circuit substrate without deflection of a wiring film on both sides of a substrate in a formation area of a hole (through hole) so as to enable further lamination of another wiring film, or the like on the wiring film, capable of forming a wiring film in a minute pattern with a necessary thickness, and a production method for the wiring circuit substrate.
To these ends, according to one aspect of the present invention, there is provided a wiring circuit substrate comprises a metal layer for forming conductor circuits, an interlayer-insulating layer formed on the metal layer, and protrusions for interconductor connection that are selectively formed on the metal layer in a state of passing through the interlayer-insulating layer and that are formed of the same metal as that for the metal layer.
In the present invention, the metal layer for forming the conductor circuits and the protrusions are formed of the same material. Therefore, a simply structured member can be used as a base member that allows the metal layer and the protrusions to be formed, thereby allowing costs for the material to be reduced. The protrusions can be formed by performing half-etching for the base member. Also, the above does not require a step of removing an interlayer-insulating layer (which will be described below), thereby allowing manufacturing time to be reduced, and also allowing reduction in the price of the wiring circuit substrate to be implemented.
According to another aspect of the present invention, a wiring circuit substrate comprises a first metal layer for forming first conductor circuits, an interlayer-insulating layer formed on the first metal layer, protrusions for interlayer connection that are selectively formed on the metal layer in a state of passing through the interlayer-insulating layer and that are formed of the same metal as that for the first metal layer, and a second metal layer that is formed on the protrusions and the interlayer-insulating layer and that is used for forming second conductor circuits.
According to the invention, a simply structured member can be used as a base member that allows forming of the metal layer and the protrusions that are selectively formed. This allows material costs to be reduced, and also, allows manufacturing time to be reduced. Accordingly, reduction in the price of the wiring circuit substrate can be implemented.
According to still another aspect of the present invention, a wiring circuit substrate comprises an insulating layer having at least one face on which first conductors of either a single layer or multiple layers are formed and openings for securing paths for electrical connection to the first conductor circuits are formed. It also comprises an interlayer-insulating layer formed on the one face of the insulating layer in which the openings are formed, protrusions formed of a conductor-forming metal layer in a state of passing through the interlayer-insulating layer at positions opposing the openings, and second conductor circuits formed on surfaces of the protrusions and the interlayer-insulating layer. In addition, the protrusions are electrically connected to the first conductor circuits through the openings, and also, electrically connects the first conductor circuits and the second conductor circuits to each other.
According to the above, the protrusions electrically connected to the first conductor circuits via the openings are provided. In short, electrical connection can be performed through the openings. This allows the wiring circuit substrate to be press-overlaid from any one of the face on which the protrusions are formed and the face on which the first conductor circuits are formed. In this case, the second conductor circuits may be a wiring circuit substrate. Thereby, a very large number of layers of conductor circuits of the wiring circuit substrate can be formed, thereby allowing the mounting density to be increased.
In the above, it is preferable that a conductive adhesion film be formed on the top of each of the protrusions. This improves the reliability of connections between the protrusions and the conductor circuits.
Also, in the above, it is preferable that each of the protrusions be formed so as to have a substantially triangular cross section. For example, with the protrusions formed of a glass-cloth-containing material that is normally used, the protrusions effectively and securely pass through the interlayer-insulating layer. Also, the protrusions are inserted into the metal layer that will be formed, thereby making characteristics of connections between the protrusions and the metal layer to be even more secure.
Also in the invention, it is preferable that the protrusions be formed in a konide-like shape. In this case, the top of each of the protrusions can be arranged to be planar, thereby avoiding the probability of making heights of the protrusions to be inconsistent. In addition, according to the protrusions, the distance (thickness) of the interlayer-insulating layer can be ensured to be at a constant value.
Also in the invention, it is preferable that each of the protrusions be formed in a drum-like shape. This allows the plain area of the top of each of the protrusions to be even larger. According to this, conductive-paste processing can be easily performed, and the reliability of the connection characteristics of the protrusions can also be improved. Concurrently, effects for ensuring the distance (thickness) of the interlayer-insulating layer to be constant can be obtained even more securely.
In addition in the invention, it is preferable that a surface of each of the protrusions be formed in a rough pattern. Also in the invention, it is preferable that a surface of each of the protrusions be subjected to particle-plating.
According to the above, since the surface of each of the protrusions is rough-patterned and particle-plated, connection characteristics between the top thereof and the metal layer can be improved.
It is preferable that the protrusions be formed of a copper material, and the surface thereof be subjected to electrolytic chromate processing.
According to the above, the protrusions are formed of a copper material, and the surface thereof be subjected to electrolytic chromate processing. Thereby, the surface of the metal layer can be prevented from being oxidized, thereby allowing the reliability of the connection between the protrusions and the metal layer.
It is preferable that the protrusions be arranged substantially in a plain matrix. In the stage before the conductor circuits on the two faces are formed by selectively performing etching, whatever is the model of the wiring circuit substrate, conductor circuits are mass-produced as standard products. Thereafter, the conductor circuits are formed so as to differ depending upon the pattern of the model of the wiring circuit substrate. This method allows improvement in the productivity of other different models of wiring circuit substrates. In addition, the masks need not be changed depending upon the model, thereby reducing the number of the copper-etching operations. Therefore, either the different-model small-quantity production or the restricted-model mass-production can be handled, thereby significantly contributing to the improvement in the economy.
In addition, it is preferable that the protrusions be formed and arranged so that pressure forces exerted when the wiring circuit substrate is stacked are uniformed for each of the protrusions. According to this, collapsed conditions of the individual protrusions can be uniformed, connection characteristics can be uniformed, and the reliability can be improved.
It is preferable that the protrusions be arranged so as to form a first area where the arrangement density is high and a second area where the arrangement density is low are formed, and dummy protrusions whose heights are smaller than those of the protrusions be formed around the first area.
According to the above, the smaller dummy protrusions are arranged around high-density arrangement areas of the individual protrusions in addition to the protrusions arranged at a high density. This allows reduction in the etching rates in peripheral areas of the high-density arrangement areas to be similar to a level of the central area. As a result, etching rates of the protrusions can be uniformed, and also, diameters and heights of the individual protrusions can be uniformed.
Also, it is preferable that each of the protrusions include dummy protrusions formed as a ring in its peripheral portion, and each adjacent couple of the dummy protrusions be formed at a spacing from each other. According to this, improved effects of the dummy protrusions at etching time can be obtained.
Each of the protrusions include dummy protrusions may be formed as a ring in its peripheral portion. Also, it is preferable that each adjacent couple of the dummy protrusions be formed so as to partially overlap with each other. According to this, areas where the dummy protrusions are formed can be minimized, and concurrently, the described effects can be obtained.
Also, it is preferable that the protrusions include a plurality of dummy protrusions formed around one of the protrusions. According to this, the uniformity of the etching rates can further be improved.
It is preferable that the protrusions include a plurality of dummy protrusions formed around a plurality of the protrusions, and also, the plurality of dummy protrusions be formed outside a forming area of the plurality of protrusions so as to be apart from each other at a predetermined spacing. According to this, etching rates for the plurality of protrusions can be uniformed.
It is preferable that the protrusions be formed to have a plurality of different heights. According to this, overlaying can be performed without causing problems on faces having different connection mechanisms, such as stepped connection faces and faces of copper paste and copper patterns.
It is preferable that the protrusions be formed to have a plurality of different diameters. According to this, diameters of the protrusions in which a high current flows can be increased, and diameters of the protrusions in which a low current flows can be reduced. This prevents problems such as that voltage drop occurs because a high voltage flows in the protrusions having small diameters, joule heat is generated, and the protrusions exclusively use unnecessarily excessive areas because the protrusions have large diameters while high current does not flow therein.
It is preferable that the second metal layer have openings formed in portions corresponding to the protrusions, the diameter of each of the openings being smaller than that of the top of each of the protrusions.
According to the above, when the protrusions are connected to the second metal layer, top portions of the protrusions abut the openings and collapse them. Accordingly, strong connections between the protrusions and the second metal layer can be ensured. This allows the reliability of the connections to be improved.
It is preferable that the protrusions include spacers formed of the same material as that for the protrusions and are formed so as to have substantially the same height as the protrusions. According to this, heights of the protrusions and the distance (thickness) of the interlayer-insulating layer are arranged to be constant, thereby allowing the impedance-controllability to be improved. The spacers may be grounded so as to be usable as an electrostatic shield.
It is preferable that the protrusions include identification marks formed of the same material as that for the protrusions and are formed so as to have substantially the same height as the protrusions. According to this, positioning and model identification can be easily carried out.
It is preferable that a plated layer be formed around each of the protrusions. Thus, since plating is performed before the protrusions are formed, the plating can be used as an etching mask. In addition, the plating improves the reliability of the connection of the protrusions.
Also, it is preferable that the conductive adhesion film be an anisotropic conductive film. In the above, since the anisotropic conductive film may be provided between the protrusions and the metal layer connected thereto, that is, metal particles in the anisotropic conductive film, the connection between the protrusions and the metal layer can be ensured.
It is preferable that the conductive adhesion film be formed by coating conductive paste material as a surface treatment agent.
In this case, since the conductive paste material is coated, the characteristics of the connections between the protrusions and the conductor circuits can be further improved.
According to still another aspect of the present invention, a wiring circuit substrate comprises a first metal layer for forming first conductor circuits, an etching-barrier layer formed of a metal differing from that of the first metal layer on the first metal layer, protrusions for interconductor connection that are made of metal and are selectively formed on the etching-barrier layer, an interlayer-insulating layer formed on the first metal layer in a state of allowing the protrusions to pass through, and a second metal layer that is formed on surfaces of the protrusions and the interlayer-insulating layer and that is used for forming second conductor circuits.
According to the above, the protrusions are selectively formed on the first metal layer via the interlayer-insulating layer. In this case, while erosion of the first metal layer is prevented according to the etching-barrier layer. Therefore, the base member either having at least the same height as that of the protrusions or a height larger than that of the protrusions can be used to obtain the wiring circuit substrate. This reduces portions of the base member in which bending, deformation, and the like may occur during the manufacture. Also, since there is no probability that the dimensions vary and positions of the protrusions horizontally deviate, even when the protrusions are finely formed to increase the arrangement density, there is no probability that defective interlayer connections between the upper and lower conductor circuits occur because of positional deviation of the protrusions. This allows the yield and the reliability to be improved.
In addition, the protrusions can be formed of metal, for example, a relatively low-priced metal such as a copper material. Thereby, compared to the conventional cases where the conductive paste formed either by filling into the openings or printing is used as the upper-lower-conductor-circuit connecting device, the wiring circuit substrate can be provided at a lower price.
Also, since the protrusions are formed by selectively performing etching for the first metal layer, heights thereof can be uniformed. Therefore, there are no probabilities that defects in the connections between the upper and lower conductor circuits occur because of inconsistent heights. In addition, the protrusions and the first metal layer are integrated into one unit, mechanical strengths of the protrusions can be higher than in the conventional cases.
It is preferable that the etching-barrier layer be formed so as to have the same width of that of a section of the protrusions. When etching is performed for the first metal layer, although the etching-barrier layer functions as an etching barrier, the etching is performed in a later step by using the protrusions as masks. Thereby, the interlayer-insulating layer formed on the first metal layer can be formed in a good condition.
It is preferable that the etching-barrier layer be formed in an area extending to reach reverse faces of the protrusions and the interlayer-insulating layer. According to this, the wiring circuit substrate that does not require a step of etching for the etching-barrier layer can be provided. In addition, the function as an etching-barrier layer can be achieved.
In addition, it is preferable that a plated layer be formed so as to cover around the protrusions and the etching-barrier layer. According to this, even in a wiring circuit substrate, the plating can be used as an etching mask, and also, the reliability of the connection of the protrusions can be secured.
According to still another aspect of the present invention, a wiring circuit substrate comprises a first wiring circuit substrate, a second wiring circuit substrate, and a third wiring circuit substrate. The first wiring circuit substrate is formed by comprising a base plate made of insulating resin, a plurality of first metal layers that is formed on an upper surface of the base plate and that are formed of first wiring circuits, a plurality of second metal layers that is formed on the lower surface of the base plate and that is formed of second wiring circuits, and through-holes that are formed so as to pass through the base plate and that electrically connect the first wiring circuits on the upper surface and the second wiring circuits on the lower surface to each other. The second wiring circuit substrate is formed on the upper surface of the base plate by comprising a first interlayer-insulating layer formed on surfaces of the base plate and the first metal layer, and a plurality of first protrusions for connecting upper and lower conductors to each other that is selectively formed in a length so as to reach the first metal layer and the through-holes in a state of passing through the first interlayer-insulating layer. The third wiring circuit substrate is formed on the lower surface of the base plate by comprising a second interlayer-insulating layer formed on surfaces of the base plate and the second metal layer, and a plurality of second protrusions for connecting upper and lower conductors to each other that is selectively formed in a length so as to reach the second metal layer and the through-holes in a state of passing through the second interlayer-insulating layer. The second wiring circuit substrate and the third wiring circuit substrate are stacked in a state where the edges of the first protrusions and the second protrusions are connected to the first wiring circuits and the second wiring circuits. Conductive paste is filled into the through-holes, and the second wiring circuit substrate and the third wiring circuit substrate are thereby electrically connected to each other.
According to the above aspect of the invention, the through-holes are formed on the base member to electrically connect the first and second metal layers to each other. The first and second protrusions are provided on the second and third wiring circuit substrate, respectively. The first and second interlayer-insulating layers are formed on faces of the second and third wiring circuit substrate on which the first and second protrusions are formed in a state of allowing the first and second protrusions to pass through.
In a state where the edges of the first protrusions are connected to the first wiring circuits formed of the first metal layer and the edges of second protrusions are connected to the second wiring circuits made of the second metal layer, the second and third wiring circuit substrates are stacked with the first wiring circuit substrate being arranged therebetween, and the wiring circuit substrate is thereby configured. According to the above, high integration is can be implemented, and in addition, improvement can be implemented for characteristics of the electric connection between the circuit substrates and the reliability of the connection.
According to still another aspect of the present invention, a wiring circuit substrate comprises a first metal layer for forming first conductor circuits; protrusions for interlayer connection that are selectively formed on the first metal layer and that are formed of the same metal as that for the first metal layer; an interlayer-insulating layer formed on a face of the first metal layer, on which the protrusions are formed, in a state of allowing the protrusions to pass through; a second metal layer that is formed on the protrusions and the interlayer-insulating layer and that is used for forming second conductor circuits; and a third metal layer arranged between the second metal layer and the protrusions.
According to the above aspect of the present invention, since the third metal layer is provided between the protrusions and the second metal layer, the reliability of electric connection characteristics of the protrusions is improved.
It is preferable that the second metal layer comprise openings that are formed on portions corresponding to the protrusions, each of the openings having a diameter larger than the diameter of each of the protrusions.
According to this, the top of each of the protrusions of the second metal layer is deeply inserted in a solder layer, a conductive-paste layer, or a noble-metal film that is filled in the opening, thereby further improving characteristics of the connections therebetween.
Also, it is preferable that the third metal layer be formed of one of a solder layer, a conductive-paste layer, and a noble-metal film. According to this, the second metal layer and the protrusions can be connected via one of the layers and the film, thereby allowing electric connection characteristics therebetween to be improved.
According to still another aspect of the present invention, a wiring circuit substrate comprises a metal layer for forming wiring circuits, an interlayer-insulating layer formed on the metal layer, protrusions for interconductor connection that are formed on the interlayer-insulating layer in a state of passing through the interlayer-insulating layer, and either conductor circuits differing from the conductor circuits or a circuit substrate that is formed on the protrusions and the interlayer-insulating layer. The interlayer-insulating layer is formed of an anisotropic conductive film.
In the above, an anisotropic conductive film is used as an interlayer-insulating layer. In this case, even with the interlayer-insulating layer being arranged between the protrusions and the metal layer, the area therebetween is allowed to become conductive; that is, the protrusions and the metal layer can securely be electrically connected to each other.
It is preferable that an anisotropic conductive film be formed either between the protrusions and the aforementioned different conductor circuits or between the protrusions and the circuit substrate. Thereby, the protrusions and the different conductor circuits can be securely connected to each other via metal particles in the anisotropic conductive film.
According to still another aspect of the present invention, a wiring circuit substrate comprises at least two first wiring circuit substrates and a second wiring circuit substrate provided between at least two units of the first wiring circuit substrates. Each of the first wiring circuit substrates comprises an insulating layer having at least one face on which first conductors of either a single layer or multiple layers are formed and openings for securing paths for electrical connection to the first conductor circuits are formed, an interlayer-insulating layer formed on the one face of the insulating layer in which the openings are formed, and protrusions formed of a conductor-forming metal layer in a state of passing through the interlayer-insulating layer at positions opposing the openings and are electrically connected to the first conductor circuits through the openings. The first wiring circuit substrates are stacked such that faces on each of which the protrusions and the interlayer-insulating layer are formed inwardly expose via the second wiring circuit substrate and are pressed. Thereby, the first wiring circuit substrates and the second wiring circuit substrate are integrated into one unit.
According to the invention, the protrusions electrically connected to the first conductor circuits via the openings are provided. The two wiring circuit substrates each having the interlayer-insulating layer are stacked such that faces on each of which the protrusions and the interlayer-insulating layer are formed inwardly expose. In this case, the two first wiring circuit substrates may be stacked either directly or via the wiring circuit substrate and are pressed. Thereby, the wiring circuit substrates are integrated into one unit. According to this configuration, the number of layers of conductor circuits of the wiring circuit substrate can be significantly increased, and mounting density can thereby be increased.
In the above, it is also preferable that the wiring circuit substrate further comprise LSI chips individually overlaid on the first wiring circuit substrates. In addition, it is preferable that the wiring circuit substrate further comprise packages individually overlaid on the first wiring circuit substrates.
According to the invention, with either the LSI chips or the packages, the wiring circuit substrate having either the LSI chips or the packaged that are mounted at high density can be obtained. This also allows miniaturization to be implemented for the wiring circuit substrate.
According to still another aspect of the present invention, a wiring circuit substrate comprises a first wiring circuit substrate, a second wiring circuit substrate stacked on the first wiring circuit substrate, and a third wiring circuit substrate stacked on the second wiring circuit substrate.
In this case, it is preferable that the individual first to third wiring circuit substrates have the aforementioned various types of the wiring circuit substrates. Thereby, the wiring circuit substrate that meets requirements for even higher density and even higher integration can be provided.
In addition, the present invention defines an electronic apparatus including one of the wiring circuit substrate as mentioned above. This allows the provision of the wiring circuit substrate of the present invention for use in the high-integration and high-density electronic apparatus.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of forming an etching-barrier layer on a first metal layer that will be formed to be first conductor circuits, and forming a second metal layer, which is used to form protrusions, on the etching-barrier layer, the etching-barrier layer being formed of a metal differing from that of the first metal layer; a step of forming the protrusions by selectively performing etching for the second metal layer by using etchant that does not etch at least the etching-barrier layer; a step of removing the etching-barrier layer by using the protrusions as masks and by using etchant that does not etch the first metal layer; a step of forming an interlayer-insulating layer on a face of the first metal layer on which the protrusions are formed; and a step of forming a third metal layer, which will be formed to be second conductor circuits, on the interlayer-insulating layer and the protrusions.
According to the above aspect, etching is selectively performed for the second metal layer for forming the protrusions by using etchant that does not etch the etching-barrier layer. Thereby, the protrusions can be forming, and only the etching-barrier layer can be removed by using etchant and by using the protrusions as masks. The protrusions connect the first and second conductor circuits to each other. Thus, the aforementioned wiring circuit substrate can be obtained.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of forming an etching-barrier layer on a first metal layer that will be formed to be first conductor circuits, and forming a second metal layer, which is used to form protrusions, on the etching-barrier layer, the etching-barrier layer being formed of a metal differing from that of the first metal layer; a step of forming the protrusions by selectively performing etching for the second metal layer by using etchant that does not etch at least the etching-barrier layer; a step of forming an interlayer-insulating layer on a face of the first metal layer on which the protrusions are formed; a step of forming a third metal layer, which will be formed to be second conductor circuits, on the interlayer-insulating layer and the protrusions; and a step of removing the first metal layer and the etching-barrier layer by performing selective etching using an etching mask layer as a mask.
According to the invention, selective etching by using the protrusions as masks is not performed for the etching-barrier layer. Specifically, the etching is performed for the etching-barrier layer together with the first metal layer for which selective etching is performed. This avoids a step that is carried out only to remove unnecessary portions of the etching-barrier layer, thereby allowing the manufacturing steps to be reduced.
Also in the invention, the step of forming the protrusions may include a step of using a fourth metal layer as an etching mask. It is preferable that the manufacturing method further comprise a step of allowing the fourth metal layer to remain and covering faces of the protrusions by using the fourth metal layer.
According to above, when etching is selectively performed for a layer made of a base metal to form the protrusions, the fourth metal layer is used as an etching mask. Even after the protrusions is formed, the fourth metal layer is allowed to remain, and the fourth metal layer is used to cover all the surfaces of the protrusions. In this case, without performing a difficult operation of coating conductive paste on the top of each of the protrusions, the fourth metal layer used as the etching mask can be used as a means for improving characteristics of the connection between the individual protrusions and the second metal layer.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of forming an etching-barrier layer on a first metal layer that will be formed to be first conductor circuits, and forming a second metal layer, which is used to form protrusions, on the etching-barrier layer, the etching-barrier layer being formed of a metal differing from that of the first metal layer; a step of forming the protrusions by selectively performing etching for the second metal layer by using etchant that does not etch at least the etching-barrier layer; a step of removing the etching-barrier layer by using the protrusions as masks and by using etchant that does not etch the first metal layer; forming an interlayer-insulating layer on a face of the first metal layer on which the protrusions are formed and forming a multilayer body; a step of forming a third metal layer, which will be formed to be second conductor circuits, on the interlayer-insulating layer and the protrusions; a step of overlaying individual metal foils on the third metal layer and the first metal layer of the wiring circuit substrate and performing pressing-heating processing therefor; and a step of selectively performing for the third metal layer and the metal foils and thereby forming the second conductor circuits, and also, selectively performing etching for the first metal layer and the metal foils and thereby forming the first conductor circuits, thereby forming the wiring circuit substrate.
According to the present invention, the wiring circuit substrate and metal foils are overlaid, and etching is selectively performed for both the first metal layer and the metal foils at the same time. This allows the provision of the wiring circuit substrate in which the first and second conductor circuits interlayer-insulated by the interlayer-insulating layer are provided on two faces, and the first and second conductor circuits are electrically connected to each other via the protrusions that pass through the interlayer-insulating layers.
Also, the manufacturing method may further comprise a step of stacking at least two units of the multilayer bodies on two faces of the wiring circuit substrate, on which the first conductor circuits and the second conductor circuits are formed, so as to be as a sandwich in a state where one face of each of the multilayer bodies faces inward, and performing pressing/heating processing therefor, thereby making an integral unit; and a step of selectively performing etching for two conductor-forming metal layers positioned on two faces of the integral unit, thereby forming conductor circuits on the two faces.
According to the above, at least two units of the multilayer body are overlaid on two faces of the wiring circuit substrate and are press-heated, and they are thereby integrated into one unit. Then, etching is selectively performed for the metal layers existing on two faces of the integral unit, thereby forming the conductor circuits on two faces thereof. Accordingly, the wiring circuit substrate having conductor circuits of four layers can be obtained.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of forming an insulating layer including openings on at least one face of conductor circuits of either a single layer or multiple layers; a step of forming protrusions that are formed of a conductor-circuit-forming metal layer at positions opposing the openings and are electrically connected to the conductor circuits through the openings; a step of forming at least two wiring circuit substrates having an interlayer-insulating layer formed on the side of the insulating layer where the protrusions are formed; a step of stacking and pressing at least two units of the wiring circuit substrates directly or via another wiring circuit substrate in a state where the sides where the protrusions and the interlayer-insulating layer are formed face inward, thereby making them into an integral unit.
According to the above, there is provided a base metal via the insulating layer having the openings in one main face of the conductor circuits of either a single layer or multiple layers. Also, there are provided the protrusions electrically connected to the conductor circuits through the openings. The two wiring circuit substrates having the interlayer-insulating layer formed on the side of the insulating layer where the protrusions are formed are stacked directly or via another wiring circuit substrate in a state where the sides where the protrusions and the interlayer-insulating layer are formed face inward, thereby making them into an integral unit. Thereby, the number of the layers of the conductor circuits of the wiring circuit substrate can be significantly increased, and the mounting density can therefore be increased.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of preparing a first metal layer used for forming first conductor circuits and selectively forming mask films on one face of the first metal layer; a step of performing half-etching for the first metal layer by using the mask films as masks, thereby selectively forming protrusions on the one face of the first metal layer; a step of forming an interlayer-insulating layer on the first interlayer-insulating layer in a state of allowing the protrusions to pass through; a step of overlaying a second metal layer, which will be formed to be second conductor circuits, on the protrusions and the interlayer-insulating layer; and a step of selectively patterning the first metal layer and the second metal layer at one time or different times, thereby forming the first conductor circuits and the second conductor circuits.
According to the invention, mask films are selectively formed on one face of the first metal layer that is used as a base member, and half-etching is performed for the first metal layer by using the mask films as masks. Subsequently, the metal layer to be formed to be the conductor circuits and the protrusions are formed. Then, the two metal layers are formed via the interlayer-insulating layer on the surface of the first metal layer (which will be formed to be the first conductor circuits) on which the protrusions are formed. Subsequently, the first and second metal layers formed on two surfaces of the interlayer-insulating layer are selectively patterned at one time or different times, thereby forming wiring films. Thereby, the wiring circuit substrate can be obtained.
It is preferable that the manufacturing method further comprise a step of forming an anisotropic conductive film on the top of each of the protrusions before overlaying the second metal layer. The anisotropic conductive film improves electrical-connection characteristics between the second metal layer and the protrusions.
It is also preferable that the manufacturing method further comprise a step of performing spray-etching for the top of each of the protrusions after forming the protrusions. This allows the surfaces of each of the protrusions to have a rough pattern.
It is preferable that the step of forming the protrusions include a step of using resist masks each having a diameter smaller than a diameter of each of the protrusions required to be formed, thereby performing half-etching. This allows spear-like protrusions to be formed.
Also, it is preferable that the step of forming the protrusions include a step of removing the masks after forming the protrusions by performing the half-etching, and a step of performing half-etching again. This allows spear-like protrusions to be formed.
Also, it is preferable that said manufacturing further comprise a step of removing unnecessary pieces of the protrusions by performing over-etching before performing patterning for the firs conductor circuits and the second conductor circuits. This allows the protrusions to be arranged and arrayed as desired. This is effective when the protrusions are formed in an arrangement from a state of a matrix-like arrangement so as to receive uniformed pressure.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of forming a plurality of first metal layers formed of first wiring circuits on an upper surface of a base plate made of insulating resin, and forming a plurality of second metal layers formed of second wiring circuits on a lower surface of the base plate. The manufacturing method also comprises a step of forming first protrusions and a first interlayer-insulating layer in a length so as to reach the first metal layer in a preliminarily arranged state where the first protrusions pass through the first interlayer-insulating layer, and forming second protrusions and a second interlayer-insulating layer in a length so as to reach the second metal layer in a preliminarily arranged state where the second protrusions pass through the second interlayer-insulating layer. The manufacturing method also comprises a step of filling conductive paste, which electrically connects the first wiring circuits on the upper surface and the second wiring circuits on the lower surface to each other, into through-holes formed so as to pass through the base plate. In addition, the manufacturing method comprises a method of overlaying the first interlayer-insulating layer on surfaces of the base plate and the first metal layer (that is, on the upper surface of the base plate), and connecting the first protrusions to the first metal layer; and overlaying the second interlayer-insulating layer on surfaces of the base plate and the second metal layer (that is, on the lower surface of the base plate), and connecting the second protrusions to the second metal layer. The step of connection to the first metal layer includes a step of allowing the first protrusions to abut openings formed in the first metal layer to have a diameter smaller than that of the top of each of the first protrusions. Also, the step of connection to the second metal layer includes a step of allowing the second protrusions to abut openings formed in the second metal layer to have a diameter smaller than that of the top of each of the second protrusions.
According to the invention, when the first and second protrusions are connected to the first and second metal layers, the top of the first and second protrusions abut each of the openings and collapses it. This further increases the strengths of connections between the first and second protrusions and the first and second metal layers, thereby allowing the reliability of the connections.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of arranging many protrusions, which are formed of metal for interconductor connection, on a surface of a first metal layer; a step of providing an interlayer-insulating layer on the surface of the first metal layer in a state of allowing the protrusions to pass through; a step of forming a second metal layer on surfaces of the interlayer-insulating layer and the protrusions, the second metal layer being formed of a metal differing from that of the first metal layer; and a step of forming spacers using the same material as that for the protrusions so as to have substantially the same heights as the protrusions at the same step of forming the protrusions.
According to the above, the spacers are formed in the same step as that of forming the protrusions. Therefore, without increasing the number of steps, by the provision of the spacers, the wiring circuit substrate can be formed that allows spacings to be secured between the spacers and the metal layers.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate, comprises a step of arranging many protrusions, which are formed of metal for interconductor connection, on a surface of a first metal layer; a step of providing an interlayer-insulating layer on the surface of the first metal layer in a state of allowing the protrusions to pass through; forming a second metal layer on surfaces of the interlayer-insulating layer and the protrusions, the second metal layer being formed of a metal differing from that of the first metal layer; and a step of forming identification marks using the same material as that for the protrusions so as to have substantially the same heights as the protrusions at the same step of forming the protrusions.
According to the above, the identification marks can be formed in the same step as that of forming the protrusions. Therefore, without increasing the number of steps, the wiring circuit substrate having the identification marks can be obtained.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate, comprises a step of forming a plurality of first metal layers formed of first wiring circuits on an upper surface of a base plate made of insulating resin, and forming a plurality of second metal layers formed of second wiring circuits on a lower surface of the base plate. The manufacturing method also comprises a step of forming first protrusions and a first interlayer-insulating layer in a length so as to reach the first metal layer in a preliminarily arranged state where the first protrusions pass through the first interlayer-insulating layer, and forming second protrusions and a second interlayer-insulating layer in a length so as to reach the second metal layer in a preliminarily arranged state where the second protrusions pass through the second interlayer-insulating layer. Also, the manufacturing method comprises a step of overlaying the first interlayer-insulating layer on surfaces of the base plate and the first metal layer (that is, on the upper surface of the base plate), and connecting the first protrusions to the first metal layer; and a step of overlaying the second interlayer-insulating layer on surfaces of the base plate and the second metal layer (that is, on the lower surface of the base plate), and connecting the second protrusions to the second metal layer. The manufacturing method also comprises a step of forming a third metal layer, which is formed of either conductive paste or a noble metal, on surfaces of the first metal layer and the second metal layer before the aforementioned connection is performed.
According to the invention, the first and second wiring circuits can be assembled with the base plate being arranged therebetween. In the assembly, since the individual first and second protrusions are connected to each other via the third metal layer (one of conductive paste and a noble-metal film), electric connection characteristics therebetween can be in a suitable condition.
Also, it is preferable that the manufacturing method further comprise a step of removing partial areas of the third metal layer that protrude from surfaces of the first metal layer and the second metal layer by polishing the surfaces of the first metal layer and the second metal layer after the third metal layer is formed. According to this, the third metal layer can be formed only in, for example, the openings in the first and second metal layers.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate, comprises a step of selectively forming protrusions for interconductor connection on a first metal layer, the protrusions being formed of the same material as that for the first metal layer; a step of forming an interlayer-insulating layer on a surface of the first metal layer on which the protrusions are formed; and a step of forming a second metal layer, which is formed to be second conductor circuits, on the interlayer-insulating layer and the protrusions. Also, the manufacturing method comprises a step of forming one of a solder layer, a conductive-paste layer, and a noble-metal film between the protrusions and the second metal layer so as to correspond to the protrusions; and a step of stacking the wiring circuit substrate by connecting the protrusions to one of the solder layer, conductive-paste layer, and the noble-metal film.
According to the invention, before the second metal layer is formed, one of the solder layer, the conductive-paste layer, and the noble-metal layer is formed so as to be overlaid on surfaces of the protrusions. According to this arrangement, high integration is achieved in the assembly, and concurrently, the wiring circuit substrate improving electric connection characteristics between the circuit substrates and the reliability of connections can be obtained.
According to still another aspect of the present invention, a manufacturing method for a wiring circuit substrate comprises a step of selectively forming protrusions for interconductor connection on a first metal layer, the protrusions being formed of the same material as that for the first metal layer. The manufacturing method also comprises a step of forming an interlayer-insulating layer on a surface of the first metal layer on which the protrusions are formed; and a step of forming a second metal layer, which is formed to be second conductor circuits, on the interlayer-insulating layer and the protrusions. In addition, the manufacturing method comprises a step of printing one of a solder layer, a conductive-paste layer, and a noble-metal film between the protrusions and the second metal layer so as to correspond to the protrusions; and a step of stacking the wiring circuit substrate by connecting the protrusions to one of the solder layer, conductive-paste layer, and the noble-metal film. The step of stacking the wiring circuit substrate includes a step of forming the configuration wherein each of the protrusions passes through the interlayer-insulating layer, and one of the solder layer, the conductive-paste layer, and the noble-metal film is connected to the protrusions.
According to the invention, the second metal layer that will be formed to be the second conductor circuits differing from the first conductor circuits are formed on the side where the protrusions are formed. Then, corresponding to the protrusions, a member on which one of the solder layer, the conductive-paste layer, and the noble-metal layer is overlaid is provided. Thereby, the wiring circuit substrate can be obtained.
Another aspect of the present invention includes a base member, and a laminating sheet to be laminated on one or both surfaces of the base member. The base member has an insulating layer and metal wiring layers formed on both surfaces of the insulating layer. Furthermore, the base member has one or a plurality of through holes formed through the metal wiring layers and the insulating layer. Moreover, the base member has one or a plurality of conductive members formed so as to fill the one or the plurality of the through holes. The laminating sheet has a wiring layer, and one or a plurality of protrusion parts formed, projecting from the wiring layer at a position facing to the one or the plurality of the through holes. Furthermore, the laminating sheet is laminated in the state with the one or the plurality of the protrusion parts and the one or the plurality of the conductive materials connected.
In the present invention, the laminating sheet is formed on one or both surfaces of the base member. At the time, since the protrusion part is connected so as to cut into the conductive material, the wiring layer comprising the laminating sheet cannot be deflected also in the vicinity of the through hole. Therefore, the film thickness can be evened at a necessary thickness, and thus minute wiring can be enabled.
Moreover, since the protrusion part and the conductive material are connected directly, the adhesion property can be strengthened, and thus the reliability of the interlayer connection can be improved. Furthermore, unlike the conventional example, the wiring layer needs not be formed by an electroless plating and a subsequent electrolytic plating of a copper film.
Still another aspect of the present invention includes a base member, a first laminating sheet to be laminated on one or both surfaces of the base member, and a second laminating sheet to be laminated outside the first laminating sheet. The base member has an insulating layer and metal wiring layers formed on both surfaces of the insulating layer. Furthermore, the base member has one or a plurality of through holes formed through the metal wiring layers and the insulating layer. Moreover, the base member has one or a plurality of conductive members formed so as to fill the one or the plurality of the through holes. The first laminating sheet has a wiring layer, and one or a plurality of protrusion parts formed, projecting from the wiring layer at a position facing to the one or the plurality of the through holes. Furthermore, the first laminating sheet is laminated in the state with the one or the plurality of the protrusion parts and the one or the plurality of the conductive materials connected.
According to the present invention, since the second laminating sheet is further laminated, a multi-layer structure of the wiring substrate can be provided by a relatively simple process.
Still another aspect of the present invention has a base member including metal wiring layers formed on both surfaces of an insulating layer, and one or a plurality of through holes formed through the metal wiring layers and the insulating layer. A step of filling the one or the plurality of the through holes of the base member with the one or the plurality of the conductive materials is included. Furthermore, a laminating sheet including one or a plurality of protrusion parts formed, projecting from the metal layer at a position facing to the metal layer and the one or the plurality of the through holes is provided. A step of laminating the laminating sheet on one or both surfaces of the base member in the state with the one or the plurality of the protrusion parts and the one or the plurality of the conductive materials connected is included. Moreover, a step of forming a wiring layer by patterning the metal layer of the laminating sheet is provided.
Furthermore, still another aspect of the present invention has a base member including metal wiring layers formed on both surfaces of an insulating layer, and one or a plurality of through holes formed through the metal wiring layers and the insulating layer. A step of filling the one or the plurality of the through holes of the base member with the one or the plurality of the conductive materials is included. Furthermore, a laminating sheet including one or a plurality of protrusion parts formed, projecting from the wiring layer at a position facing to the wiring layer and the one or the plurality of the through holes is provided. A step of laminating the laminating sheet on one or both surfaces of the base member in the state with the one or the plurality of the protrusion parts and the one or the plurality of the conductive materials connected is included. Moreover, a step of further forming one or a plurality of laminating sheets substantially same as the laminating sheet on the surface of the laminating sheet is included.
According to the present invention, a multi-layer structure of the wiring substrate can be provided by a relatively simple process of preparing a base member and a laminating sheet, selective etching necessary for forming a wiring layer, and laminating the laminating sheet and the base member.
Moreover, by increasing the number of the laminating sheets to be laminated, a multi-layer structure of the wiring circuit substrate can easily be achieved so that a further high integration of the wiring circuit substrate can be realized.